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A Chemist Comes Very Close to a Midas Touch
In a lab in Princeton University’s ultra-sleek chemistry building, researchers toil in a modern-day hunt for an elusive power: alchemy.
Throughout the centuries, alchemists tried in vain to transform common metals like iron and lead into precious ones like gold or platinum. Today,Paul Chirik, a professor of chemistry at Princeton, has managed a new twist on the timeworn pursuit.
Dr. Chirik, 39, has learned how to make iron function like platinum, in chemical reactions that are crucial to manufacturing scores of basic materials. While he can’t, sadly, transmute a lump of iron ore into a pile of valuable jewelry, his version of alchemy is far more practical, and the implications are wide-ranging.
The process could herald a new era of flexible manufacturing technologies, while enabling companies to steer clear of scarce elements as prices rise or obtaining them becomes environmentally or geopolitically risky.
“No chemist would think lithium was in short supply,” Dr. Chirik said, “but what happens if you put a lithium battery in every car? This is why chemistry needs to be ahead of the curve. We need to have adaptable solutions.”
Despite the cost and relative scarcity of precious metals — iridium, platinum, rhodium — we rely on them to manufacture products from denim to beer, pharmaceuticals to fuel cells. The elements are used as catalysts, substances that kick off or enable chemical reactions.
Dr. Chirik’s work involves dissolved catalysts, which are mixed into the end product. The molecules of the catalyst dissipate during the reaction. For instance, a solution containing platinum is used to make silicone emulsifiers, compounds that in turn feed products like makeup, cookware and glue. Tiny amounts of the expensive metal are scattered in all these things; your jeans, for instance, contain unrecoverable particles of platinum.
“We’re not about to run out of platinum,” said Matthew Hartings, a chemist at American University in Washington, “but this process spends that platinum in a nonsustainable way.”
Dr. Chirik’s chemistry essentially wraps an iron molecule in another, organic molecule called a ligand. The ligand alters the number of electrons available to form bonds. It also serves as a scaffold, giving the molecule shape. “Geometry is really important in chemistry,” Dr. Hartings said. Dr. Chirik’s “ligands help the iron to be in the right geometry to help these reactions along.”
In addition to iron, Dr. Chirik’s lab also works with cobalt, which sits beside iron on the periodic table. Using cobalt, Dr. Chirik said, the scientists have generated “a whole new reaction that no one has ever seen before.” It produces new types of plastics using very inexpensive starting materials.
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